Many utility and entertainment services, such as cable television ("TV"), require the use of customer premises equipment ("CPE"). A service provider may use such CPE to control the services received by each customer. For example, a video interdiction unit, commonly referred to as a "cable TV box," while permitting the reception of basic services, can block the receipt of premium services, such as pay-per-view movies, unless it is programmed by the service provider to receive such services. Thus, a service provider can independently control the capability of a customer to receive only the services that the customer has subscribed to, and paid for, by selectively-configuring the CPE provided to that customer.
When a piece of CPE is not subject to a service provider's continuous control, it is possible for the CPE to be tampered with by a customer. For example, a customer may alter the operation of the CPE to allow the customer to receive services that the customer has not subscribed to or paid for. Because of this, service providers have developed and used various tamper detection methods, some of which merely allow a service provider to detect whether the CPE has been tampered with, and some which disable the CPE if an attempt is made to tamper with it.
A simple tamper detection method employs a physical seal, such as an adhesive tape, which must be detectably broken before the CPE chassis can be opened. Although this method is very inexpensive, it can only alert the service provider to potential tampering if the CPE is physically examined on a periodic basis. Thus, the use of this method is generally limited to those services that require regular field inspections independent of the need to deter and detect tampering; e.g., for use-based services, such as electricity, that require periodic meter-reading to determine service usage.
A second method used to deter tampering employs a mechanical device that destructively disables a critical component of the CPE if an attempt is made to tamper with it, thus requiring a customer that attempts to tamper with the CPE to call the service provider and request either a new CPE or servicing of the disabled device. While this method eliminates the need for a service provider to conduct periodic inspections to detect tampering, it is more costly than other alternatives due to the need for replacement of the disabled component.
A third method to deter CPE tampering employs an electrical sensor that detects when a door of a CPE chassis is opened. The electrical sensor provides a signal to circuit logic, contained within the CPE, that disables the operability of the CPE, thus requiring a customer that attempts to tamper with the CPE to call the service provider in order to restore service. This method also eliminates the need for a service provider to conduct periodic inspections to detect tampering. If a customer removes the source of electrical power to the CPE before tampering with it, and closes the chassis door before restoring electrical power thereto, however, the electrical sensor is incapable of providing a signal to the circuit logic designed to disable the device. Thus, this method cannot prevent tampering by those customers who understand how the tamper detection mechanism operates.
Accordingly, what is needed in the art is a security system and method for detecting chassis tampering that does not require period field inspections, does not require the replacement of disabled circuit components, and which cannot be circumvented by removing electrical power from the device within the CPE chassis.